Video function

Dual Integrated Video Low Pass Reconstruction Filter Output Summer Composite Video Integrated output driver provides low impedance output and transmits 2VP-P (6dB gain) video into 150 Ω. 7.1MHz 4th order video filter 7.1MHz Y and C filter with CV output 42dB stopband attenuation at 27MHz on Y, C and CV Flatness better than 1dB on Y, C and CV to 4.5 MHz No external frequency selection 9ns group delay flatness on component or clock Y, C and CV outputs AC-coupled input and output 0.4% differential gain, 0.4° differential phase Integrated low-slope DC recovery/clamping circuit

application

CCTV Cable and Satellite Set-Top Box DVD Player TV Personal Video Recorder (PVR) Video on Demand (VOD) Distribution Amplifier

General Instructions

The FMS6410 dual-channel video filter driver chip CV Summer provides a comprehensive video filter box or DVD application for set-top boxes. This part consists of two 4th order Butterworth 7.1MHz video signal low pass filters. This filter is optimized for low overshoot and flat group delay. The device also contains a summing circuit to generate the filtered composite video. Integrated video drivers include driving directly to the outside world. In a typical application, the Y and C input signals from the DAC are AC coupled to the filter. Both channels have DC restore circuitry to clamp the DC input level sync during video. Y and C channels use separate feedback clamps. The clamp pulse is from the Y channel. The output is AC coupled. The Y, C, and CV outputs are buffered to drive 2VP-P into a 150Ω load (1VP-P into a double-terminated 75Ω coaxial load) with up to 35pF of capacitance at the output pins. The Y, C and CV channels have a gain level of approximately 2 (6dB) for a 1VP P input. There is an option for the video output to be DC coupled, which limits the driver output to one output channel per driver.

Introduction to function description

The FMS6410 is a dual MCU continuous time video filter for reconstructing luminance and chrominance signals from S-Video D/A sources. The composite video output is the output generated by adding the filtered Y and C. The chip is used for AC applications coupled in and AC coupled out (see Figure 1). This reconstruction filter approximates the fourth order Butterworth with towards low overshoot and flat group delay. The Y, C, and CV outputs are capable of driving 2VP-P into an AC-coupled 150Ω video load with a maximum load capacitance of 35pF at the output. All channels are clamped during synchronization to establish the proper output voltage swing range. Therefore, the input coupling capacitor does not work according to the traditional RC time constant. Clamp video input source changes that sink below 10 mV within 5 ms for all channels. In most applications, the input coupling capacitor is 0.1µF. The Y and C inputs typically sink 1 microamp during active video, which nominally slopes about 2mV horizontally at the Y output. During synchronization, the clamp is typically sourced from 20µA to restore the DC level.

The end result is zero average input current. Any change in the value of the input coupling capacitor will inversely change the amount of slope of each line. Such changes will also linearly affect the clamp response time. This product is robust and stable under all specified load and input conditions. Capacitive bypassing of VCC directly to ground ensures this. Luminance (Y) I/Oluma input consists of 1VP-P or 75Ω terminated line output. The input is required to be AC coupled through a 0.1µF coupling capacitor which allows a settling time of 5ms. The luma output is capable of driving an AC-coupled 150Ω load with 2VP-P, or 1VP-P into a double-terminated 75Ω load. Up to 35pF with no stability or slew issues. The output is AC coupled with a 220µF or larger AC coupling capacitor.

Chroma (C) I/O Chroma input consists of 0.7VP-P or 75Ω terminated line output. The input is required to be AC coupled through a 0.1µF coupling capacitor allowing a clamp set-up time of 5ms. The output is capable of driving an AC coupled 150Ω load, 2VP-P or 1VP-P into a double terminated 75Ω load. Load capacitance up to 35pF can be used without stability or many problems. A 0.1µF AC coupling capacitor is recommended at the output. Because the chrominance signal does not contain low frequency components, the smaller 0.1µF capacitor is recommended not to use the 220µF cap to reduce circuit cost. Composite Video (CV) Output The composite video output is capable of driving 2 loads 2VP-P. Used to drive TVs and VCRs. Either the TV input or the VCR input may be shorted to ground and the other output will still be within specs. Load capacitance up to 35pF (at the output pin) can drive under unstable conditions or solve problems. The DC-coupled output applies a 220µF capacitor coupled with a 150Ω termination to form a high pass filter that passes the video frequency and avoids tilt. Lower values such as 10 microF can cause problems. With AC coupling, the average DC level is zero. Therefore, the output voltages of all channels will be centered around zero. Alternatively, DC coupling allows the output of the FMS6410. There are several trade-offs: the average DC level of the outputs is 2V; each output will nominally consume an additional 40 MW; the application needs to accommodate the 1V DC offset sync tip; it is recommended to limit each output to a 150Ω load.

ABSOLUTE MAXIMUM RATINGS (DEVICE MAY DAMAGE)

NOTE: None of the functional operation under these conditions is implied. Performance and reliability are guaranteed not to exceed operating conditions only under the following conditions.

Electrical Characteristics of 1Vp-p Input Signal at Room Temperature

Electrical Characteristics of 1Vp-p Input Signal at Room Temperature (Continued)

notes:

1.330pF peak capacitance adds nominally 0.7dB to 4.2MHz output

2. Continuous short circuit protection limited to 10 seconds

3. Feature Guarantee